/* Copyright 2013 Google Inc.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
 * USA.
 *
 * Project home page: http://code.google.com/p/usb-serial-for-android/
 */

package com.stu.usb;

import android.hardware.usb.UsbDevice;
import android.hardware.usb.UsbDeviceConnection;

import java.io.IOException;

/**
 * A base class shared by several driver implementations.
 *
 * @author mike wakerly (opensource@hoho.com)
 */
abstract class CommonUsbSerialDriver implements UsbSerialDriver {

	public static final int DEFAULT_READ_BUFFER_SIZE = 16 * 1024;
	public static final int DEFAULT_WRITE_BUFFER_SIZE = 16 * 1024;

	protected final UsbDevice mDevice;
	protected final UsbDeviceConnection mConnection;

	protected final Object mReadBufferLock = new Object();
	protected final Object mWriteBufferLock = new Object();

	/** Internal read buffer.  Guarded by {@link #mReadBufferLock}. */
	protected byte[] mReadBuffer;

	/** Internal write buffer.  Guarded by {@link #mWriteBufferLock}. */
	protected byte[] mWriteBuffer;

	public CommonUsbSerialDriver(UsbDevice device, UsbDeviceConnection connection) {
		mDevice = device;
		mConnection = connection;

		mReadBuffer = new byte[DEFAULT_READ_BUFFER_SIZE];
		mWriteBuffer = new byte[DEFAULT_WRITE_BUFFER_SIZE];
	}

	/**
	 * Returns the currently-bound USB device.
	 *
	 * @return the device
	 */
	public final UsbDevice getDevice() {
		return mDevice;
	}

	/**
	 * Sets the size of the internal buffer used to exchange data with the USB
	 * stack for read operations.  Most users should not need to change this.
	 *
	 * @param bufferSize the size in bytes
	 */
	public final void setReadBufferSize(int bufferSize) {
		synchronized (mReadBufferLock) {
			if (bufferSize == mReadBuffer.length) {
				return;
			}
			mReadBuffer = new byte[bufferSize];
		}
	}

	/**
	 * Sets the size of the internal buffer used to exchange data with the USB
	 * stack for write operations.  Most users should not need to change this.
	 *
	 * @param bufferSize the size in bytes
	 */
	public final void setWriteBufferSize(int bufferSize) {
		synchronized (mWriteBufferLock) {
			if (bufferSize == mWriteBuffer.length) {
				return;
			}
			mWriteBuffer = new byte[bufferSize];
		}
	}

	@Override
	public abstract void open();

	@Override
	public abstract void close();

	@Override
	public abstract int read(final byte[] dest, final int timeoutMillis);

	@Override
	public abstract int write(final byte[] src, final int timeoutMillis);

	@Override
	public abstract void setParameters( int baudRate, int dataBits, int stopBits, int parity);

	@Override
	public abstract boolean getCD() throws IOException;

	@Override
	public abstract boolean getCTS() throws IOException;

	@Override
	public abstract boolean getDSR() throws IOException;

	@Override
	public abstract boolean getDTR() throws IOException;

	@Override
	public abstract void setDTR(boolean value) throws IOException;

	@Override
	public abstract boolean getRI() throws IOException;

	@Override
	public abstract boolean getRTS() throws IOException;

	@Override
	public abstract void setRTS(boolean value) throws IOException;

}
